Chemoenzymatic Route Research Articles

A Chemoenzymatic Route to a Class of Sucrose Esters

Sucrose esters are the most developed carbohydrate esters and are used in the food, cosmetic, and pharmaceutical industries. Herein, we introduce a novel chemoenzymatic pathway for the synthesis of β‐d‐fructofuranosyl‐(2,1)‐α‐d‐uronic acid derivatives, a new class of sucrose esters.

Whole cell biocatalysts for the preparation of nucleosides and their derivatives.

This work makes particular emphasis on the following methods: the biocatalyzed whole cell synthesis of nucleosides mediated by phosphorylases, key biocatalyzed steps involved in other chemoenzymatic routes to prepare nucleoside analogues and the transformation of nucleosides in derivatives with particular properties. The literature covered in this work confirms that biocatalytic procedures that make use of whole cell systems can be successfully applied to obtain a wide variety of nucleoside analogues and their derivatives, providing alternative and complementary routes to traditional chemistry. The direct use of microbial whole cells as biocatalysts affords competitive results since it avoids the cumbersome procedures involved in enzyme isolation and facilitates multienzymatic processes. These biocatalysts also maintain the enzymes in their natural environment, protecting their activities from reaction conditions. Although the information presented herein shows that these methodologies have reached a high degree of development, it is expected that future contributions of protein engineering and nucleoside metabolism knowledge, among other disciplines, will expand the already wide range of applications in nucleoside chemistry of whole cell biocatalysis.

Studies on asymmetric synthesis of bicyclomycin precursors. A chemoenzymatic route to chiral 2,5-diketopiperazines and 2-oxa-bicyclo[4.2.2]decane-8,10-diones

A novel asymmetric route to bicyclomycin analogues, 2-oxa-bicyclo[4.2.2]decane-8,10-diones, is described. The key chiral synthons 3-(ω-hydroxyalkyl)-2,5-diketopiperazines 3a-c were obtained via enzymatic kinetic resolution of their respective acetates 2a-c using hydrolases (up to >98% ee, E>200). The chiral 2,5-diketopiperazines were then transformed into their bicyclic derivatives in a stereospecific manner. Circular dichroism and NMR studies were performed to determine the absolute and relative configuration of the obtained products. The biocatalytic approach gave high stereoselectivities in comparison to the chiral pool synthesis from glutamic acid (58% ee) and thus demonstrated the ability of hydrolases to discriminate a remote stereocenter.

Chemoenzymatic Route to Chiral Gamma Secretase Inhibitor Intermediates

Key words large-scale synthesis - transaminase - alcohol dehydrogenase - medicinal chemistry - drugs

Efficient chemoenzymatic synthesis of gabapentin by control of immobilized biocatalyst activity in a stirred bioreactor

Gabapentin has been widely used for the treatment of epilepsy and neuropathic pain in the world. In this work, an efficient and greener chemoenzymatic manufacturing process for gabapentin has been developed. The whole cells expressing engineered nitrilase were immobilized in diatomite cross-linked with polyethyleneimine and glutaraldehyde to improve their reusability and stability for the synthesis of gabapentin intermediate 1-cyanocyclohexaneacetic acid from 1-cyanocyclohexaneacetonitrile. The initial enzyme activity in the bioreactors at each batch biotransformation was maintained at a constant value by introducing fresh immobilized cells into the system to keep the high conversion (100%) and the same operation time (8h) in each batch. The resulting 1-cyanocyclohexaneacetic acid was then converted to gabapentin efficiently by simple chemical steps. An E factor (exclude water) of 11.5 was calculated for the chemoenzymatic route relative to 55.7 for the mentioned chemical process. This new route dramatically improved process efficiency compared to the chemical process.

A Chemoenzymatic Route to Chiral Intermediates Used in the Multikilogram Synthesis of a Gamma Secretase Inhibitor

A chemoenzymatic route for the production of an intermediate to a gamma secretase inhibitor is described. The route is robust and was run at multikilogram scale. The process employs both a transaminase catalyzed reductive amination of a substituted tetralone and an alcohol dehydrogenase catalyzed reduction of an α-ketoester to generate the two chiral centers in the molecule, with nearly perfect stereoselectivity. The process also features simple isolation schemes, including a direct drop isolation of the aminotetralin phosphate salt.

Exploiting the Biocatalytic Toolbox for the Asymmetric Synthesis of the Heart‐Rate Reducing Agent Ivabradine

AbstractSeveral chemoenzymatic routes have been evaluated for the production of the heart‐rate reducing agent ivabradine. Lipases and ω‐transaminases have been identified as useful biocatalysts for the preparation of key enantiopure precursors. The lipase‐catalysed kinetic resolution by alkoxycarbonylation of a racemic primary amine and subsequent chemical reduction of the resulting carbamate provided an N‐methylated (S)‐amine, one step away from ivabradine. Alternatively, the dynamic kinetic resolution by asymmetric bioamination of an aldehyde precursor enabled, in a four‐step sequence, the preparative scale synthesis of enantiopure ivabradine in 50% overall yield.magnified image

Rapid chemoenzymatic route to glutamate transporter inhibitor l-TFB-TBOA and related amino acids.

The complex amino acid (l-threo)-3-[3-[4-(trifluoromethyl)benzoylamino]benzyloxy]aspartate (l-TFB-TBOA) and its derivatives are privileged compounds for studying the roles of excitatory amino acid transporters (EAATs) in regulation of glutamatergic neurotransmission, animal behavior, and in the pathogenesis of neurological diseases. The wide-spread use of l-TFB-TBOA stems from its high potency of EAAT inhibition and the lack of off-target binding to glutamate receptors. However, one of the main challenges in the evaluation of l-TFB-TBOA and its derivatives is the laborious synthesis of these compounds in stereoisomerically pure form. Here, we report an efficient and step-economic chemoenzymatic route that gives access to enantio- and diastereopure l-TFB-TBOA and its derivatives at multigram scale.

Chemoenzymatic preparation of optically active cyclic 4-hydroxy-acylaziridines

A highly enantioselective chemoenzymatic route to cyclic 4-hydroxyacylaziridines is described.

Chemoenzymatic route to optically active dihydroxy cyclopenta[b]naphthalenones; precursors for decalin-based bioactive natural products

The development of an efficient chemoenzymatic route for the synthesis of optically active dihydroxy cyclopenta[b]naphthalenones; (+)-1,4a-dihydroxy-4a,5,6,7,8,8a,9,9a-octahydro-1H-cyclopenta[b]naphthalen-2(4H)-one (+)-10 and (+)-1,8a-dihydroxy-4a,5,6,7,8,8a,9,9a-octahydro-1H-cyclopenta[b]naphthalen-2(4H)-one (+)-11 is described. Different lipases and esterases were tested in the enzymatic hydrolysis of the corresponding acetates (±)-4a-hydroxy-2-oxo-2,4,4a,5,6,7,8,8a,9,9a-decahydro-1H-cyclopenta[b]naphthalen-1-yl acetate (±)-8, (±)-8a-hydroxy-2-oxo-2,4,4a,5,6,7,8,8a,9,9a-decahydro-1H-cyclopenta[b]naphthalen-1-yl acetate (±)-9, CRL (Candida Rugosa Lipase) and PLE (Pig Liver Esterase) were found to be the most effectual enzymes; for (−)-8 by 47% ee with the corresponding dihydroxy; (+)-10 by 98% ee in the presence of CRL; whereas, (−)-8 was obtained with 40% ee with the corresponding dihydroxy, (+)-10 with 58% ee in the PLE hydrolysis. It was concluded that CRL was the best biocatalyst for the substrate (±)-8. Moreover, enzymatic resolution in the presence of CRL yields, (−)-9 with 46% ee with the corresponding dihydroxy derivative; (+)-11 with 98% ee; however, in the presence of PLE, yields (−)-9 with 36% ee as well as the related dihydroxy derivative; (+)-11 with 49% ee respectively. The study concluded that CRL is the best biocatalyst for compounds (±)-8 and (±)-9.

THE IMPACT OF CHAIN EXTENDER ON THE PROPERTIES OF POLYURETHANE FOAM BASED ON RAPESEED OIL POLYOL OBTAINED VIA CHEMO–ENZYMATIC ROUTE

Presently, researches regarding green chemistry are conducted due to its significance for the mitigation of environmental problems, particularly those related to carbon dioxide emissions in relation to global warming and the usage of fossil feedstocks not only for energy generation but also for materials production. The study examines the impact of bio-products such as corn starch, rapeseed glycerin as well as petroleum based propylene glycol as bifunctional and trifunctional chain extenders on physical-mechanical properties of polyurethane foam from rapeseed oil polyol derived via chemo-enzymatic route. The obtained foams were characterized using European and international methodologies for determination of density, compressive strength perpendicular and parallel to foaming directions, thermal conductivity, long-term water absorption after 28 days of immersion, closed cell content and cell size. Foams containing (5–25) pphp of corn starch display significantly lower values in density and compressive strength as well as cell size compared to the neat polyurethane foam. The greatest compressive strength and the lowest thermal conductivity are obtained for foams with 25 pphp of rapeseed glycerin. All foams extended with bio-products and propylene glycol are characterized by the higher long-term water absorption compared to that of the neat polyurethane foam.

ChemInform Abstract: A Chemoenzymatic Route to Prepare Acyclic Nucleoside Analogues

Abstractinvolving an aldol condensation of aldehydes of various nucleobases catalyzed by a dihydroxyacetone phosphate‐dependent aldolase (rabbit muscle aldolase)

Piperidine-based glycodendrons as protein N-glycan prosthetics

The generation of homogeneously glycosylated proteins is essential for defining glycoform-specific activity and improving protein-based therapeutics. We present a novel glycodendron prosthetic which can be site-selectively appended to recombinant proteins to create ‘N-glycosylated’ glycoprotein mimics. Using computational modeling, we designed the dendrimer scaffold and protein attachment point to resemble the native N-glycan architecture. Three piperidine–melamine glycodendrimers were synthesized via a chemoenzymatic route and attached to human growth hormone and the Fc region of human IgG. These products represent a new class of engineered biosimilars bearing novel glycodendrimer structures.

A chemoenzymatic route to chiral siloxanes

An approach employing two enzymes—toluene dioxygenase and immobilized lipase B from Candida antarctica (N435)—was explored as a potential biocatalytic method for the coupling of chiral diols with siloxane species. Analysis of reaction mixtures using 1H NMR spectroscopy suggested that up to 66% consumption of the siloxane starting materials had occurred. Oligomeric species were observed and chiral products from the coupling of a cyclic diol with a siloxane molecule were isolated and characterized by MALDI-ToF MS and GPC.Immobilized lipases from Rhizomucor miehei and Thermomyces lanuginosus were also explored as potential catalysts for the coupling reactions, however, their use only returned starting material.

An Efficient Chemoenzymatic Synthesis of Coenzyme A and Its Disulfide

We have developed a chemoenzymatic route to coenzyme A (CoASH) and its disulfide that is amenable to gram-scale synthesis using standard laboratory equipment. By synthesizing the symmetrical disulfide of pantetheine (pantethine), we avoided the need to mask the reactive sulfhydryl and also prevented sulfur oxidation byproducts. No chromatography is required in our synthetic route to pantethine, which facilitates scale-up. Furthermore, we discovered that all three enzymes of the CoASH salvage pathway (pantetheine kinase, phosphopantetheine adenyltransferase, and dephospho-coenzyme A kinase) accept the disulfide of the natural substrates and functionalize both ends of the molecules. This yields CoA disulfide as the product of the enzymatic cascade, a much more stable form of the cofactor. Free CoASH can be prepared by in situ S–S reduction.

Tuning lipase-catalysed kinetic resolution of 2-substituted thiophenes and furans: A scalable chemoenzymatic route to masked γ-bis-oxo-alcohols

The demand for greener and applicable approaches aiming at the synthesis of optically active compounds as single enantiomers has seen a significant growth worldwide. Since most of the chemically synthesized compounds are produced as racemates their kinetic resolution has been of great interest. For this purpose a number of chemo-enzymatic approaches were proposed. One of such approaches, the use of isolated lipases, is a well-established alternative. Herein we report the kinetic resolutions of 2-Substituted five-membered heteroaromatic rings. By optimizing the reaction conditions it was possible to produce (2-hydroxy)-2-substituted furans and thiophenes in high enantiomeric ratio (E>200). Thus, racemic mixtures of compounds with slight structural differences were resolved. The current chemo-enzymatic strategy has been applied to a scalable approach leading to the formation of the enantiopure (S)-2i a well-known building block used for the synthesis of bioactive natural compounds.

A Chemoenzymatic Route To Prepare Acyclic Nucleoside Analogues

AbstractAcyclic nucleosides are potential antiviral and antitumor agents. In this work, their preparation through a novel chemoenzymatic procedure involving the N‐alkylation of a nucleobase and subsequent aldol condensation catalyzed by a dihydroxyacetone phosphate‐dependant aldolase (Rabbit Muscle Aldolase, RAMA) is described.

Chemoenzymatic Route for the Synthesis of (S)-Moprolol, a Potential β-Blocker.

A biocatalytic route for the synthesis of a potential β-blocker, (S)-moprolol is reported here. Enantiopure synthesis of moprolol is mainly dependent on the chiral intermediate, 3-(2-methoxyphenoxy)-propane-1,2-diol. Various commercial lipases were screened for the enantioselective resolution of (RS)-3-(2-methoxyphenoxy)propane-1,2-diol to produce the desired enantiomer. Among them, Aspergillus niger lipase (ANL) was selected on the basis of both stereo- and regioselectivity. The optimized values of various reaction parameters were determined such as enzyme (15 mg/mL), substrate concentration (10 mM), organic solvent (toluene), reaction temperature (30 °C), and time (18 h).The optimized conditions led to achieving >49% yield with high enantiomeric excess of (S)-3-(2-methoxyphenoxy)propane-1,2-diol. The lipase-mediated catalysis showed regioselective acylation with dual stereoselectivity. Further, the enantiopure intermediate was used for the synthesis of (S)-moprolol, which afforded the desired β-blocker.

Development of a Chemoenzymatic Route to (R)-Allyl-(3-amino-2-(2-methylbenzyl)propyl)carbamate

A chemoenzymatic route to (R)-allyl-(3-amino-2-(2-methylbenzyl)propyl)carbamate (1-(R)) has been developed on a kilogram scale. The key intermediate, 2-(2-methylbenzyl)propane-1,3-diamine 4, was isolated as a tartrate salt in a three-step sequence starting from 2-methylbenzyl chloride. The subsequent lipase-catalyzed desymmetrization was optimized, and 1-(R) was isolated as the d-tartrate salt.

Synthesis of reversed structured triacylglycerols possessing EPA and DHA at their terminal positions

This report describes synthesis of reversed structured triacylglycerols (TAGs) of the LML type, possessing pure EPA or DHA located at the terminal 1,3-positions of the glycerol backbone along with pure even number saturated fatty acids (C6:0–C16:0) occupying the 2-position. These compounds were synthesized by a two-step chemoenzymatic route involving a highly regioselective immobilized Candida antarctica lipase to incorporate EPA or DHA activated as acetoxime esters exclusively into the 1,3-positions of glycerol. The saturated fatty acyl groups were subsequently introduced to the remaining 2-position by EDCI coupling agent to accomplish the title compounds highly efficiently. This is the first report on reversed structured TAGs possessing the long-chain n-3 polyunsaturated fatty acids. It is anticipated that these novel compounds and their synthetic methodology will find various important uses such as analytical standards, in screening for bioactivity and in the pharmaceutical area as prodrugs.